(a) Field of the Invention
The present invention relates to a device and method for detecting timing synchronization.
(b) Description of the Related Art
A communication system of an orthogonal frequency division multiplexing (OFDM) method is technology that divides all channels into narrowband subchannels having orthogonality and transmits the narrowband subchannels, and can effectively overcome selective fading of a frequency. Such an OFDM method sustains orthogonality of a symbol by inserting a cyclic prefix of a longer cycle than a delay spread of a channel into a front end of the symbol, thereby removing intersymbol interference (ISI), and thus the OFDM method is effective for high-rate data transmission.
However, a merit of the OFDM method is obtained only when orthogonality between subcarriers is sustained, and when orthogonality is not sustained, interchannel interference (ICI) occurs and thus system performance is deteriorated. Therefore, in a system of the OFDM method, it is important to synchronize time and frequency of a receiving apparatus.
A receiving apparatus such as a mobile station performs timing synchronization of an OFDM signal using a preamble signal that is transmitted by a base station. In general, the preamble includes an effective symbol having a constant fast fourier transform (FFT) size and a cyclic prefix that is inserted in front of the effective symbol. The cyclic prefix is equal to a signal of a last segment of an effective symbol.
A method of acquiring timing synchronization using such a preamble calculates a symbol timing metric that is defined based on a preamble structure, and regards a position of a specimen that maximizes a result thereof as a start position of the preamble. In this case, the preamble is obtained by loading a specific progression in an even-numbered subcarrier and performing an inverse fast fourier transform (IFFT), and thus an effective symbol has two specimen units that are repeated one time at a time axis.
Detection of a symbol timing metric can be performed by using only an interrelationship between repetition patterns existing in an effective symbol without considering an interrelationship between a cyclic prefix and an effective symbol. However, in such a method, a flat area is displayed in the symbol timing metric, and symbol timing estimate is not accurate.
Further, detection of a symbol timing metric may be performed in consideration of an interrelationship between a cyclic prefix and an effective symbol. However, in such a method, a flat area is not displayed in the symbol timing metric, but dispersion of the symbol timing estimate is large and thus performance of other algorithm blocks may be deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.